PET/CT scan

A PET/CT (Positron Emission Tomography Computed Tomography) scan combines a CT scan and a PET scan into one. The scan uses X-ray technology together with a radioactive tracer to produce a detailed three-dimensional picture of your internal anatomy and function.


Before your treatment begins, you’ll be offered a PET/CT scan. The scan helps us identify cancerous targets called tumour receptors so we can precisely plan your treatment.

What is a PET/CT Scan?

A PET/CT scan combines two imaging techniques: Positron Emission Tomography (PET) and Computerised Tomography (CT). PET produces 3-D images of your body and allows us to look at your metabolism and other important functions. We can also study any changes that are happening over time while we monitor your condition. The CT scan uses computer-processed X-ray measurements to create a detailed image.

How does it work?

Before carrying out a PET/CT scan, a ‘tracer’ (a type of radioactive substance) will be injected in to your arm, hand, or foot. The tracer spreads through the body and gives off a type of radiation that shows up on the PET scan. This allows the scanner to build up a detailed image that identifies areas of the body affected by disease, as well as some of the body’s functions.

The PET scans are combined with CT scans which adds the precision of anatomic localisation to functional imaging enabling a more accurate diagnosis. The CT scanner takes a series of cross-sectional images (‘slices’) and then computer processing is used to construct a three-dimensional image.

Using this method, we can get important information about many conditions affecting different parts of the body. The combination of scans shows the precise shape, location and size of your tumour. It helps your specialist to make an accurate diagnosis and plan the best treatment for you. The scan is safe and doesn’t hurt.

Having a PET/CT scan

A radiographer will ask you to lie on the scanner bed and make you as comfortable as possible. The scanner bed will move gently and slide you into the centre of the scanner until the part of the body to be scanned is correctly positioned. While the scan is taking place, you’ll need to remain still.

The scan takes between 20 and 45 minutes but there’s also some preparation time, so you’ll need to allow about two hours for the appointment.


The amount of radioactivity injected in the tracer is relatively small and will be excreted by your kidneys (passed when you urinate). It will not produce any side effects. You can eat, drink and travel as normal after the test. However, as a precaution, we advise our patients to avoid having close contact with young children and pregnant women for 4 – 6 hours after leaving the department.

The test is not advised if you are pregnant or are breast feeding.

Philip's experience of a PET/CT scan

Find out more

For more information about a private PET/CT scan at GenesiscCare please call:

Oxford:01865 706 098

Windsor: 01753 343 213

Or complete the enquiry form below and we’ll come back to you – usually within 24 hours

Make an enquiry